One further note on the above formula. This formula was devised in England. I have absolutely nothing to confirm it could be used for US pressures IE I have nothing to confirme a load which recorded 3 tons under the British systemn would in fact record 6720 LUP in a US pressure gun. R'Mans very good post shows the problems that could be encountered. These crusher pressure measurements served a most needed purpose in their day, but were at that time usually listed as "PSI". I do not recall for certain when the terms LUP & CUP began to be widely used, but care must be used in interpreting older pressure listings as to what was actually meant. Actual true PSI will always be equal to or higher than a crusher pressure, never lower.
